package com.hmdp.utils;

import cn.hutool.core.lang.UUID;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;

import javax.annotation.Resource;
import java.util.Collections;
import java.util.concurrent.TimeUnit;

/**
 * 分布式锁
 */
public class SimpleRedisLock implements ILock {


    private StringRedisTemplate stringRedisTemplate;
    private String name;
    private static final String KEY_PREFIX = "lock:";
    private static final String ID_PREFIX = UUID.randomUUID().toString(true)+"-";
    private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;
    static {//static静态代码款随着类的初始化时加载执行,而不用每次调用时加载
        UNLOCK_SCRIPT = new DefaultRedisScript<>();
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("lock.lua"));
        UNLOCK_SCRIPT.setResultType(Long.class);
    }
    public SimpleRedisLock(String name,StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
        this.name = name;
    }
    @Override
    public boolean tryLock(Long timeouitSec) {
        //获取线程标识
        String threadId = ID_PREFIX+ Thread.currentThread().getId();
        Boolean success = stringRedisTemplate.opsForValue().setIfAbsent(KEY_PREFIX+name, threadId, timeouitSec, TimeUnit.SECONDS);
        //避免空指针的风险
        return Boolean.TRUE.equals(success);
    }

    @Override
    public void unlock() {
        //释放时防止释放到别人的锁
        String threadId = ID_PREFIX+ Thread.currentThread().getId();//获取线程ID
        String id = stringRedisTemplate.opsForValue().get(KEY_PREFIX + name);
        if(threadId.equals(id)) {
            stringRedisTemplate.delete(KEY_PREFIX+name);
        }
    }
}
